In the next few posts, we’ll unpack some of the statistical terms that the GRE throws around. These terms can be seen as ways to answer two main questions:
- What’s Typical
- What’s Possible
In the former category, we have the median, mean, and mode. Essentially, these give you a sense of what the average value is, or what the most common value is. They give you a sense of what a typical value might be.
In the latter category, we have the range, quartiles, and percentiles. These give you a sense of the possibilities and how the values are distributed.
In later posts, we will give actual definitions of these concepts. But first, some overarching advice about learning these concepts.
There are four main ways you’ll get tested on these concepts.
- Given some data and asked to compute the value of one of these terms.
- Given some data and told to alter the data in some way (e.g. by adding 10 to every value) and then compute the value of one of these terms.
- Given some graph/chart and asked to estimate the value of one of these terms.
- Asked a question that requires knowledge of some property of these concepts (e.g. that interquartile range is always less than the range).
So you want to understand the formal definition well enough to do 1 and 2, but also have some intuitive sense for the concepts (which can help in doing problems of type 3 or 4). In what follows, we’ll try to help in building that intuitive sense for these concepts.